Yes and no. I've seen published authorship attribution (AA) papers that used 13 submissions, so compared to that it is big.
I don't know why this branch of NLP/machine learning has been fairly okay with small corpora. When I did my last project we used 100 authors which was a lot compared to most of the literature at the time.
On the flip side, the only AA papers I've seen that use a large corpus are projects that scrape blogs, and I think it is safe to say that the traditional stylometric features are not optimized for that kind of language.
I don't know why this branch of NLP/machine learning has been fairly okay with small corpora. When I did my last project we used 100 authors which was a lot compared to most of the literature at the time.
On the flip side, the only AA papers I've seen that use a large corpus are projects that scrape blogs, and I think it is safe to say that the traditional stylometric features are not optimized for that kind of language.